If goods are not genuine, then product counterfeiting has occurred. If goods have been diverted from their intended channel of commerce by, for example, entering into a country where the goods are prohibited by contract or by law, then the goods have been subject to product diversion.
Product counterfeiting occurs on artworks, CDs, DVDs, computer software recorded on CDs or diskettes, perfumes, designer clothes, handbags, briefcases, automobile and airplane parts, securities (e.g. stock certificates), identification cards (driver's licenses, passports, visas, green cards), credit cards, smart cards, and pharmaceuticals. According to the World Health Organization, more than 7% of the world's pharmaceuticals are bogus. This percentage is higher in some countries, such as Colombia, where up to 40% of all medications are believed to be fake. Until recently, the percentage of bogus medications in the United States has been virtually negligible due to a tightly controlled regulatory system has made it extraordinarily difficult for counterfeiters to sell or distribute suspect medications. However, the recent explosion of Internet drug sales from other countries and increasingly sophisticated counterfeiting techniques have substantially increased the amount of fraudulent drugs entering the United States.
Product diversion has also occurred on many of the aforementioned goods. Such diversion could result in the sale and distribution of goods which do not comply with the product specifications required in the markets they are sold. For example, motorcycles intended to be sold without catalytic converters in a region with lower air pollution standards might be diverted to a region which requires catalytic converters. Other negative effects include price inequities in certain markets, loss of exclusivity by some manufacturers or distributors, and damage to the goodwill, patent rights, and trademark rights of the manufacturer. Such diverted goods are sometimes referred to as “gray market” goods. Since the goods are genuine, it is sometimes difficult to determine whether the goods have been improperly diverted. This is especially true for a variety of goods such as, for example clothing, pharmaceuticals, and cosmetics.
The application of security markers or taggants to a object or product for authenticating the origin and intended market of the object product are known in the prior art. These security markers can be incorporated into components which make up the object or can be incorporated into papers, inks, or varnishes that are applied to the object or into labels affixed to the object or packaging for the object. The presence of security markers verifies the authentic origin of the object and is verified by means suited to the particular nature of the marker.
Detection methods for markers are diverse and are suited to the particular nature of the marker. Detection methods can be destructive or non-destructive. An example of a destructive detection method is elemental analysis of the chemical composition of the object and applied marker. Elemental analyses usually require the chemical digestion of a part of the object and analysis of the resulting solution to quantify the elements or compounds contained therein. Destructive methods are, therefore, time consuming and costly.
More conveniently, detection methods are non-destructive. For example, authentication devices can be used which detect the optical or magnetic properties of markers, in situ, without the need to alter or destroy the object on which they reside. A very common non-destructive method of authentication is the detection of specific reflective, absorptive, or emissive responses of marker materials. Emissive materials are common as security markers.
Security markers are of two types, depending on the solubility of the marker material in the carrier used to apply it to an item. In the first instance, if a marker is dispersed in a varnish carrier and it is not soluble in that varnish, it is referred to as a particle-based or a pigment-based marker. Particle-based or pigment-based markers remain intact in the varnish and will appear as particles when examined microscopically. In the second instance, the marker material dissolves in the ink or varnish and is distributed in the carrier on a molecular level. Such markers are referred to as dyes. No discrete marker particles are observed when examining the marked carrier microscopically. A given marker can act as a dye in one carrier, in which it is soluble, and as a particle-based marker in a different carrier, in which it is not soluble.
Organic materials are sometimes defined as materials which contain at least one carbon to hydrogen bond. Examples of inorganic emissive materials which can be used as particulate markers in most inks, varnishes and other carriers are given in U.S. Pat. No. 6,436,314 (Oshima et al.), and in the reference T. Soukka et al., Photochemical Characterization of Up-Converting Inorganic Lanthahide Phosphors as Potential Labels, Journal of Fluorescence, Vol. 15, No. 4, July 2005, pp. 513-528. Additional examples include, but are not limited to: CaWO4: Eu; CaMoO4: Mn, Eu; BaFBr: Eu; Y2O2S:Tb; Y2O2S:Er, Yb; Y2O2S:Er; Y2O2S:Eu; Y2O3: Eu; Y2O2S: Eu+Fe2O3; Gd2O2S:Tb; Gd2O2S: Eu; Gd2O2S: Nd; Gd2O2S: Yb, Nd; Gd2O2S: Yb, Tm; Gd2O2S:Yb, Tb; Gd2O2S: Yb, Eu; LaOF:Eu; La2O2S:Eu; La2O2S:Eu Tb; La2O2S:Tb; BaMgAl16O27:Eu; Y2SiO5: Tb, Ce; Y3Al5O12: Ce; Y3Al2.5Ga2.5O12: Ce; YVO4: Nd; YVO4: Eu; Sr5(PO4)3Cl:Eu; CaS:Eu; ZnS: Ag, Tm and Ca2MgSi2O7:Ce, ZnS: Cu, ZnS: Cu, Au, Al; ZnS: Ag; ZnSiO4: Mn; CaSiO3: Mn, ZnS: Bi; (Ca, Sr)S: Bi; (Zn, Mg)F2: Mn; CaWO4; CaMoO4; ZnO: Zn; ZnO: Bi, and KMgF3: Mn. Particulate markers can be made up of organic or inorganic materials.
Examples of emissive pigments are available on the websites of vendors Epolin, Fabric Color Holding Inc., Beaver Luminescers, and LDP LLC dyes and pigments. A specific example of a material which can be used as an organic emissive pigment UVXPBR, a UV excitable material, emitting red visible light available at www.maxmax.com. UVXPBR is insoluble in water and can be used to produce aqueous-based dispersions containing emissive organic pigment particles.
Any group of particles contains particles in a distribution of sizes. A group of particles can be characterized by a mean particle size and a standard deviation characterizing the deviation of particles in the group from the mean of the group. Groups of particles can be characterized as monodispersed if 90% of the particles (1.645 times the standard deviation) have sizes within +/−5% of the mean size for the group. If less than 90% of the particles have sizes within 5% of the mean, than the particles are considered to be polydispersed. Most particulate security markers are polydispersed.
Particles are described as having a multimodal distribution of sizes if a plot of number (frequency) of particles of a given size versus size shows more than one maximum. Each maximum in the plot is referred to as a mode. For instance, if a plot has two maxima, the particle size distribution is said to be bimodal. If a plot has one maximum, the particle size distribution is said to be monomodal. Here, if a collection of particles has a multimodal distribution of sizes, we will refer to the selection of particles corresponding to a given mode as a group of particles.
Particles sizes can be characterized by a variety of methods. These include methods where particles are suspended in a liquid and analyzed by electroresistance methods such as the Coulter Counter, sedimentation methods, laser diffraction or acoustic spectroscopic analysis. Before executing a particle size measurement, it is important to ensure that particles are well-dispersed in the liquid and particles have not aggregated into clusters made up of two or more particles. Particle deaggregation is usually achieved by the homogenization and/or sonication of the particle suspension and, occasionally by the addition of chemical dispersants which coat the particle surfaces and limit aggregation.
Particles can exist in many shapes; however, particle diameters measured by the methods noted above are often quoted in terms of an equivalent-spherical-diameter (ESD). This is the diameter of the sphere with the same volume as the volume of the actual, often non-spherical particle.
Different types of mean particle diameters can be obtained and the type obtained depends on the measurement technique used to obtain the particle size distribution. The examples below use volume-weighted mean ESD and standard deviations to characterize the particle distributions. A complete definition and discussion of different types of mean particle diameters including volume-weighted mean diameter, is given by Maarten Alderliesten, Mean Particle Diameters Part II: Standardization of Nomenclature, Particles and Particle System Characterization, Volume 8, 1991, pp. 237-241.
The authenticity of emissive markers and objects containing emissive markers, is based on features of their emissive response. Features used for authentication of emissive markers include excitation wavelength or wavelengths, emission wavelength or wavelengths, emission intensity, and temporal duration of the emission. An emissive marker will emit only if excited with an appropriate excitation wavelength and will not emit if excited with other excitation wavelengths. Thus, the authentication of an item bearing an emissive marker may be based on the presence of an emissive response in a specific spectral region when the marker is illuminated with electromagnetic radiation in a specific spectral region. The authentication may additionally require the absence of an emissive response in a specific spectral region when the marker is illuminated with electromagnetic radiation in a specific spectral region. Authentication criteria may require that the detected marker emission be within a range of intensities (luminance range) when measured with a given detection system.
For detection systems capable of measuring the temporal evolution and decay of the marker emissive response, authentication criteria may be based on the temporal parameters of this response. Thus, an emissive marker is characterized by a set of parameters including excitation and emission wavelength responses, emission intensity, and emission temporal response. Detection systems can be built to detect one or more of these parameters. Sophisticated detection systems not only detect marker parameters but also test whether they fall within authentication specifications. If all specified parameters are detected and they fall within the authentication specifications, then the item containing the emissive marker is deemed to be authentic. The set of marker parameters detected for authentication and the authentication criteria represent a security marker code.
One approach used to increase the security of marked items is to combine multiple markers, in specific ratios, to generate a new security marker code. As marker codes become more complex, requiring multiple excitation sources and the ability to detect emission at multiple wavelengths, the cost of the detection system increases. This is especially disadvantageous when it is necessary to widely distribute detection systems, for example, to authenticate tickets, passports or other secure documents.
A further disadvantage of authenticating the presence of security markers solely based on emissive characteristics is that, given sufficient expertise and resources, counterfeiters can evaluate the emissive response of goods containing security markers. Counterfeiters can then purchase marker materials necessary to replicate this emissive response, and apply these marker materials to counterfeit goods.
Security providers often endeavor to keep security marker levels low and to hide security markers in selected regions of marked goods; however, as instrumental technology improves, prices for spectrometers capable of detecting low marker levels drop, and the technology required to detect and replicate marker codes become more widely accessible. Additionally, access to security markers has increased with the increase of the number of security companies with internet sites offering direct sale of such markers, with minimal customer screening.
The present invention uses responses related to marker size and size distribution as part of the marker code, providing a less expensive method of generating a more complex, difficult-to-replicate security code.